Deadly Design

Wider, Straighter Roads Aren't Necessarily Safer Ones -- As The Avon Intersection Where Four People Were Killed Just Over A Week Ago Clearly Shows

August 07, 2005|By Toni Gold Toni Gold of Hartford is a senior associate with Project for Public Spaces, a nonprofit whose mission is to creating public places that build community. In that capacity, she teaches context-sensitive design to highway engineers. She writes regularly for The Courant's Place pages.

It was only a matter of time before a horrible crash would occur at the intersection of routes 44 and 10 in Avon, as one did July 29. Is there a soul living west of the Connecticut River who hasn't driven through that intersection many times? Even I, who live in Hartford, work at home and drive only 3,000 miles a year, am intimately familiar with it. A slightly less treacherous intersection waits on the West Hartford side of Avon Mountain, at the Route 44 intersection with Mountain Road.

These intersections, like many others in Connecticut, are designed to be deathtraps. A shocking statement? Think about it: Why wouldn't a motorist speed downhill on that steep, five-lane, seemingly uncrowded highway, with its unimpeded sight line the last quarter-mile and a green light beckoning at the end? Why wouldn't all those under-occupied, overly wide lanes feel perfectly safe at 50 or even 65 mph?

Oh, no, you might say, Route 44 meets all standards. Right, it does. But there can be other goals for road design besides automobile mobility, which takes precedence over all other goals in the design of most state roads in Connecticut.

Among the design factors that help promote automobile mobility are, for example, the concept of ``level of service,'' with grades from A to F. LOS measures vehicle delay at intersections -- the higher the grade, the faster traffic flows.

Don't get me wrong; safety is always a requirement, too. Those fat technical manuals that only engineers can decipher are replete with safety standards, from geometric design to signage. You can be sure that Route 44 meets most, if not all, of them -- lane width, curvature, grades, horizontal and vertical alignment, signing, sight distance, shoulder width and all the rest. But the goal of mobility drives everything else, partly because many people believe that wider, flatter and straighter equal safer -- but, of course, also faster, which the public demands.

What's Real Safety?

But safety is a funny thing. There is ``nominal safety,'' and then there is ``substantive safety,'' an interesting distinction made by a thoughtful highway safety researcher, Ezra Hauer. He defined ``nominal safety'' as measured by adherence to all those standards that Route 44 undoubtedly meets, whereas ``substantive safety'' is measured by the actual performance of the road, which means the frequency, type, severity and other characteristics of crashes. Imagine that.

The posted speed limit on Route 44 is 40 mph. But for most drivers, certainly those on Route 44, the posted speed limit is fairly irrelevant. That's because every road has a ``design speed,'' which is always higher than the posted speed limit -- presumably to provide a cushion of safety (yes, they do that on purpose). Like level of service, design speed is basically a subjective decision by the design engineer, a decision from which virtually all characteristics of the road flow. This is a decision about how dangerous a road is going to be.

Another bias in favor of the design goal of mobility: Almost all highway improvements for safety and congestion relief are designed for peak traffic at the height of rush hour -- kind of like the shopping mall that creates a parking lot big enough to accommodate every shopper on Christmas Eve, then sits empty the rest of the year. For roads, this practice is a menace. It means that the going-to-work side of the road is almost empty in the evening, and the going-home side almost empty in the morning -- an invitation for vehicles going against the rush-hour flow to speed -- which was exactly the situation on Avon Mountain the Friday before last, when the dump truck heading west down the mountain crashed into four lanes of eastbound commuter traffic queued up at the traffic light.

Road-building practices are replete with such technical biases in favor of increasing automobile flow. Arcane tables and formulas allow engineers to protect themselves from liability and give ``expert'' advice that laymen and policy-makers don't dare challenge. What can challenge this formidable technical wall is simple common sense. In that regard, the concept of nominal vs. substantive safety is a real breakthrough -- an engineering concept that anyone can understand.

Look at the crash rate -- 55 collisions from 2002 through 2004 within 100 yards of that intersection, and 365 crashes on both sides of the mountain in the past five years -- and you tell me: Is Route 44 safe?

Police will try to reconstruct what happened in Friday's crash, and there will be lawsuits. Politicians will promise such things as rumble strips, stricter speed enforcement and cracking down on truck inspections. All these need to be done. But they are distractions from the real issue -- roads that are designed to kill, that meet all the nominal safety standards but few of the substantive ones.